The biogas reactors, MR, are produced under personal management and have a residence time which is about half the time compared to conventional reactors. The high capacity of the reactors makes the reactor relatively small compared to what is considered to be normal. The reactor is manufactured in a variety of sizes which makes it suitable even for customers with a low production of biological waste. The substrate is fed to a horizontal cylinder and passes through the reactor in a continuous flow. The construction makes it possible for the four stages of digestion (hydrolysis, acidogenesis, acetogenesis and methaneogenesis) to take place without affecting each other.